/*
 *  Copyright 2013 National Institute of Advanced Industrial Science and Technology
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.sss.mapreduce;

import org.sss.mapreduce.datatype.Packable;

/**
 * SSS uses <code>Partitioner</code> to determine which storage node
 * should keep a tuple.
 */
public interface Partitioner {
  /**
   * Get a partition number where the given key-value tuple  should go.
   *
   * @param  key            a key object of a tuple
   * @param  value          a value object of a tuple
   * @param  numPartitions  number of partitions to distribute
   * @return the partition number where the specified key-value tuple should go
   */
  int getPartition(Packable key, Packable value, int numPartitions);
}
